Bonnema's office building sits on a massive concrete shell projecting from a core of 10 x 10 m. containing lifts and toilets. The traditional office layout is offset by the high-powered exterior with its precast concrete elements and strong vertical thrust. With just the core on the ground floor, the rest of the modest site could be freely filled in with low-rise. The building has an extension (1977-1982) by F.J. van Gool.